diff --git a/CHANGELOG.md b/CHANGELOG.md
index 35b3c4e..2ad827f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@
 * Add date to GHC bindist names created by ghcup
 * Warn when /tmp doesn't have 5GB or more of disk space
 * Allow to compile GHC from git repo wrt [#126](https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/126)
+* Allow to set custom ghc version when running 'ghcup compile ghc' wrt [#136](https://gitlab.haskell.org/haskell/ghcup-hs/-/issues/136)
 * Add stack support
 
 ## 0.1.14.2 -- 2021-05-12
diff --git a/app/ghcup/Main.hs b/app/ghcup/Main.hs
index f0497f3..cf10529 100644
--- a/app/ghcup/Main.hs
+++ b/app/ghcup/Main.hs
@@ -174,6 +174,7 @@ data GHCCompileOptions = GHCCompileOptions
   , crossTarget  :: Maybe Text
   , addConfArgs  :: [Text]
   , setCompile   :: Bool
+  , ovewrwiteVer :: Maybe Version
   }
 
 data UpgradeOpts = UpgradeInplace
@@ -762,6 +763,15 @@ ghcCompileOpts =
           (long "set" <> help
             "Set as active version after install"
           )
+    <*> optional
+          (option
+            (eitherReader
+              (first (const "Not a valid version") . version . T.pack)
+            )
+            (short 'o' <> long "overwrite-version" <> metavar "OVERWRITE_VERSION" <> help
+              "Allows to overwrite the finally installed VERSION with a different one, e.g. when you build 8.10.4 with your own patches, you might want to set this to '8.10.4-p1'"
+            )
+          )
 
 
 toolVersionParser :: Parser ToolVersion
@@ -1571,6 +1581,7 @@ Report bugs at <https://gitlab.haskell.org/haskell/ghcup-hs/issues>|]
                   Right _ -> pure ()
                 targetVer <- liftE $ compileGHC
                             (first (GHCTargetVersion crossTarget) targetGhc)
+                            ovewrwiteVer
                             bootstrapGhc
                             jobs
                             buildConfig
diff --git a/lib/GHCup.hs b/lib/GHCup.hs
index b6821b5..47729dc 100644
--- a/lib/GHCup.hs
+++ b/lib/GHCup.hs
@@ -1324,6 +1324,7 @@ compileGHC :: ( MonadMask m
               , MonadFail m
               )
            => Either GHCTargetVersion GitBranch          -- ^ version to install
+           -> Maybe Version            -- ^ overwrite version
            -> Either Version FilePath  -- ^ version to bootstrap with
            -> Maybe Int                  -- ^ jobs
            -> Maybe FilePath           -- ^ build config
@@ -1347,7 +1348,7 @@ compileGHC :: ( MonadMask m
                  ]
                 m
                 GHCTargetVersion
-compileGHC targetGhc bstrap jobs mbuildConfig patchdir aargs
+compileGHC targetGhc ov bstrap jobs mbuildConfig patchdir aargs
   = do
     AppState { pfreq = PlatformRequest {..}
              , ghcupInfo = GHCupInfo { _ghcupDownloads = dls }
@@ -1411,8 +1412,11 @@ compileGHC targetGhc bstrap jobs mbuildConfig patchdir aargs
         lift $ $(logInfo) [i|Git version #{ref} corresponds to GHC version #{prettyVer tver}|]
 
         pure (tmpUnpack, tmpUnpack, GHCTargetVersion Nothing tver)
+    -- the version that's installed may differ from the
+    -- compiled version, so the user can overwrite it
+    let installVer = maybe tver (\ov' -> tver { _tvVersion = ov' }) ov
 
-    alreadyInstalled <- lift $ ghcInstalled tver
+    alreadyInstalled <- lift $ ghcInstalled installVer
     alreadySet <- fmap (== Just tver) $ lift $ ghcSet (_tvTarget tver)
     when alreadyInstalled $ do
       lift $ $(logWarn) [i|GHC #{prettyShow tver} already installed. Will overwrite existing version.|]
@@ -1420,7 +1424,7 @@ compileGHC targetGhc bstrap jobs mbuildConfig patchdir aargs
         "...waiting for 10 seconds before continuing, you can still abort..."
       liftIO $ threadDelay 10000000 -- give the user a sec to intervene
 
-    ghcdir         <- lift $ ghcupGHCDir tver
+    ghcdir         <- lift $ ghcupGHCDir installVer
 
     bghc <- case bstrap of
       Right g    -> pure $ Right g